studies on waste heat recovery system and design of shell and tube heat exchanger using visual basic...

7/22/2019 STUDIES ON WASTE HEAT RECOVERY SYSTEM AND DESIGN OF SHELL AND TUBE HEAT EXCHANGER USING VISUAL

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STUDIES ON WASTE HEAT RECOVERY SYSTEM AND

DESIGN OF SHELL AND TUBE HEAT EXCHANGER

USING VISUAL BASIC

&

STUDIES ON CIRCULATING FLUIDISED BED

A PROJECT REPORT

Submitted by

SELLAVEL.E (10CHR052)

SUKE.S (10CHR056)

SUTHAKAR.V (10CHL074)

in partial fulf ilment of the requirements

for the award of the degree

of

BACHELOR OF TECHNOLOGY

IN

CHEMICAL ENGINEERING

DEPARTMENT OF CHEMICAL ENGINEERING

SCHOOL OF CHEMICAL AND FOOD SCIENCES

KONGU ENGINEERING COLLEGE

(Autonomous)

PERUNDURAI ERODE638 052

APRIL 2014


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(Autonomous)

PERUNDURAI ERODE638052

APRIL 2014

BONAFIDE CERTIFICATE

This is to certify that the Project report entitled STUDIES ON WASTE HEAT

RECOVERY AND DESIGN OF SHELL AND TUBE HEAT EXCHANGER USING

VISUAL BASIC AND STUDIES ON CIRCULATING FLUIDISED BED is the

bonafied record of project work done by SELLAVEL.E (10CHR052), SUKE.S

(10CHR056), SUTHAKAR.V (10CHL074) in partial fulfilment of the requirements for

the award of the Bachelor of Technology in Chemical Engineeringof Anna university

Chennai during the year 2013 2014.

SUPERVISOR HEAD OF THE DEPARTMENT

(Signature with seal)

Date:

Submitted for the end semester viva voce examination held on___________

INTERNAL EXAMINER EXTERNAL EXAMINER


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(Autonomous)

PERUNDURAI ERODE 638052

APRIL 2014

DECLARATION

We affirm that the Project Report titled STUDIES ON WASTE HEAT RECOVERY

USING AMMONIA WATER SYSTEM AND DEVELOPMENT OF VISUAL BASIC

APPLICATION FOR DESIGN OF SHELL AND TUBE HEAT EXCHANGER

STUDIESS ON CIRCULATING FLUIDISED BED being submitted in partial

fulfilment of the requirements for the award of Bachelor of Engineering is the original

work carried out by us. It has not formed the part of any other project report or dissertation

on the basis of which a degree or award was conferred on an earlier occasion on this or any

other candidate.

Date: SELLAVEL.E

(Reg.No.10CHR052)

SUKE.S(Reg.No.10CHR056)

SUTHAKAR.V

(Reg.No.10CHL074)

I certify that the declaration made by the above candidates is true to the best of my

knowledge.

Name and Signature of the Supervisor with seal

Date:


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ABSTRACT

STUDIES ON WASTE HEAT RECOVERY AND DESIGN OF SHELL

AND TUBE HEAT EXCHANGER USING VISUAL BASIC

A combined refrigeration cycle uses ammonia and water mixture as a working fluid

to produce power and refrigeration in the same cycle. The parameters are varied to

influence the cycle are heat source temperature, boiler pressure, ammonia mass fraction,

ratio of working and heating fluid flow rates. This cycle produces the power of about 88.4

KW. The material and the energy balances of the individual equipment is done for this

cycle. Using the values obtained from above energy balances, the design of shell and tube

heat exchanger is made by the application software Visual Basic.


The circulating fluidised bed is cylindrical vessel with conical bottom is used as a

reactor with inlet from bottom of the vessel. Dead zones are formed around the cylindrical

wall of the reactor, due to this catalyst were lumped in.The lump of catalyst produces a

sudden rise in temperature, the spiral type agitator with one end suspended and other free

end will be suitable to overcome this problem. Lab scale experimental set up was

fabricated. The hydrodynamic study was carried out using the starch solution and bio

catalyst (ragi).The effect of flow rate, fluid properties such as viscosity, density and the

solid loading on the solid circulation rate and the pressure drop were studied was made and

the graphs were plotted. From results that the circulating fluidized bed with agitator gives

better performance.


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ACKNOWLEDGEMENT

First of all we thank the almighty, who is behind all our endeavours and blessed us

in completing the project successfully. We thank our beloved correspondent

Thiru. V.K. Muthuswamy, B.A., B.L., and all the members of Kongu Vellalar Institute

of Technology Trust at this high time for providing us with plethora of facilities to

complete our project successfully.

We take it a privilege to express our profound thanks to our beloved principal

Prof. S.Kuppuswami B.E., M.Sc., Dr.Ing (France) who has been a bastion of moral

strength and a source of incessant encouragement to us.

We express our sincere thanks to Head of the Chemical Engineering department

Dr.K.Saravanan, M.Tech., Ph.D., (Tech) for his valuable guidance and suggestion.

We also take this opportunity to express a deep sense of gratitude to our project

guide DR.K.Kannan, M.Tech., Ph.D., Associate professor for his exemplary guidance,monitoring and constant encouragement throughout the course of this project.

We take immense pleasure to express our heartfelt thanks to our beloved project

coordinator Dr.V.Chitra Devi, M.Tech., Ph.D.,Associate Professor for his valuable and

constant support provided all through the course of the project.

We also thank the non-teaching staff members of Chemical Engineering

Department and all our fellow students who stood with us to complete our project

successfully. We also extend our warm thanks to our beloved parents.


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TABLE OF CONTENTS

CHAPTER No. TITLE PAGE No.

ABSTRACT iv

LIST OF FIGURES viii

LIST OF SYMBOLS ix

STUDIES ON WASTE HEAT RECOVERY

AND DESIGN OF SHELL AND TUBE

HEAT EXCHANGER USING VISUALBASIC

1 INTRODUCTION 2

2 LITERATURE REVIEW 3

3 SYSTEM DESCRIPTION 4

4 MASS BALANCES 6

4.1 FLASH SEPARATOR 6

5 ENERGY BALANCES 8

5.1 FLASH SEPARATOR 8

5.2 SUPER HEATER 9

5.3 TURBINE 10

5.4 ABSORBER 11

5.5 REFRIGERATION 12

5.6 HEAT EXCHANGER 12

5.7 VAPOURISER 14

6 DESIGN OF SHELL AND TUBE HEAT

EXCHANGER

15

6.1 VISUAL BASIC CODING 21

7 CONCLUSION 29

REFERENCES 30


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CHAPTER No. TITLE PAGE No.

STUDIES ON CIRCULATING

FLUIDISED BED

1 INTRODUCTION 32

2 LITERATURE REVIEW 34

3 MATERIALS AND METHODS 35

3.1 MATERIALS USED 35

3.2 METHODS USED 36

4 EXPERIMENTAL SET UP 37

4.1 EXPERIMENTAL PROCEDURE 37

5 RESULTS AND DISCUSSIONS 38

6 CONCLUSION 44

REFERENCES 45


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LIST OF FIGURES

FIGURE No. TITLE PAGE No.

STUDIES ON WASTE HEAT RECOVERY AND

DESIGN OF SHELL AND TUBE HEAT

EXCHANGER USING VISUAL BASIC

3.1 FLOW SHEET FOR AMMONIA WATER SYSTEM 5

5.1 FLASH SEPERATOR 7

5.2 SUPER HEATER 8

5.3 TURBINE 95.4 ABSORBER 10

5.5 REFRIGERATION 11

5.6 HEAT EXCHANGER 11

5.7 VAPOURISER 13

6.1 SHELL AND TUBE HEAT EXCHANGER 26

6.2 SHELL AND TUBE HEAT EXCHANGER APPLICATION 27

STUDIES ON CIRCULATING FLUIDISED

BED

3.1 SPIRAL AGITATOR 35

4.1 EXPERIMENTAL SETUP 37

5.1 CONCENTRATION (gm/lit) Vs. FLOW RATE

(ml/sec)(without stirrer)

40

5.2 CONCENTRATION (gm/lit) Vs. FLOW RATE (ml/sec)

(with stirrer)

42

5.3 PRESSURE DROP (N/m2) Vs. FLOW RATE (ml/sec) 42


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LIST OF SYMBOLS

S.

No

Unit

Operations

Inlet

Tempera

-ture

Outlet

Temperature

Mass

in

Mass

out

Inlet

energy

Outlet

energy

Energy

added

Work

done

1Flash

Separator

2

Super

Heater

3Turbine

4Absorber

5Refrigeration

6Heat

exchanger

7 Vaporiser


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STUDIES ON WASTE HEAT RECOVERY AND DESIGN OF

SHELL AND TUBE HEAT EXCHANGER USING

VISUAL BASIC


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CHAPTER 1

INTRODUCTION

Multi-component working fluids in power cycles exhibit variable boiling

temperatures during the boiling process which make them suitable for a sensible heat

source. The temperature difference between the heat source and the working fluid remains

small to allow for a good thermal match between the source and working fluid, such that

less irreversibility results during the heat addition process.

A Novel ammoniawater binary mixture thermodynamic cycle capable of

producing both power and refrigeration has been proposed by Go swami. An ammonia

water mixture is used as it exhibits desirable thermodynamic properties in terms of a large

heat capacity. Ammonia is relatively inexpensive, can accommodate system designmodifications well and separates easily from internal lubricating oils.

Ammonia is also environmentally benign in comparison to other binary mixtures

used in industry. The cycle takes advantage of the varying boiling temperatures of the

ammonia/water mixtures to get a better there.

mal match with a sensible heat source. It also takes advantage of the low boiling

temperature of ammonia vapour to provide refrigeration. This cycle is designed as a

bottoming cycle for utilizing waste heat from a conventional power cycle or as an

independent cycle using low temperature sources such as geothermal and solar energy.

This cycle produces maximum efficiency compared to other forms of the cycles.


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CHAPTER 2

LITERATURE REVIEW

D. Yogi Goswami (2001) Novel Combined Power and Cooling ThermodynamicCycle for Low Temperature Heat Sources. This cycle can be used as a bottoming

cycle using waste heat from a conventional power cycle or as an independent cycle

using low temperature sources such as geothermal and solar energy

Kyoung Hoon Kim, Giman Kim, and Chul Ho Han (2012) PerformanceAssessment of Ammonia-Water Based Power and Refrigeration Cogeneration

Cycle. This study employs design for various combinations of power and

refrigeration and this cycle was optimized for efficiency with power.

M. M. Rashid, O.A. Beg and A. Aghagoli (2012) Utilization of waste heat incombined power and ejector refrigeration for a solar energy source intended

output. This study employs the combined power and refrigeration cycle which

combines the Rankine cycle and the ejector refrigeration cycle for a solar energy

heat source

Na Zhanga, Noam Liorb (2007) Methodology for thermal design of novelcombined refrigeration/power binary fluid systems; International Journal of

Refrigeration. This study employs Refrigeration cogeneration systems which

generate power alongside with cooling improve energy utilization.

Shaoguang Lu and D. Yogi Goswami (2002) Theoretical analysis of ammonia-based combined power/refrigeration cycle at low refrigeration temperatures. This

study employ a new combined power/refrigeration cycle uses ammonia/ water

mixture as a working fluid to produce both power and refrigeration in the same

cycle. The cycle may be designed for various combinations of power and

refrigeration.


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CHAPTER 3

SYSTEM DESCRIPTION

Ammonia water mixture (50% ammonia & 50% water) is sent into the vaporiser

where the feed is heated by the waste heat source and it is partially vaporised and then it is

sent to the flash separator where the vapour and liquid streams get separated. The ammonia

vapour at 100c and 1 bar is sent to the super heater where the vapour is heated to 50 0c and

10 bar is sent to the turbine where the gas expands to low temperature and then the power

is produced by the turbine. The output of the turbine is sent to the absorption tower and the

liquid stream from the flash separator is cooled in the recovery heat exchanger and sent to

the absorber .They get mixed and the mixture is available at low temperature. This stream

is sent to the air cooler for air conditioning system where the sensible heat is utilised for air

cooling. After utilisation of sensible heat, it is sent to the heat exchanger where the stream

is heated to some extent and then sent to the vaporiser and thus the cycle continues.

The method used for the shell and tube heat exchanger design here is the KERNs

method. Since more iterations are required and also for optimisation of the design, we

developed the Shell & Tube application software using the VISUAL BASIC Software.

This tool is very effective for the preliminary design of the shell and tube heat exchanger.

Initially the charts are converted into the respective equations and these equations are

written as a code in this tool and then all the formulas required to calculate the heat load,

LMTD, Number of passes and Number of tubes required, heat transfer coefficient, pressure

drop, heat transfer area and Overall heat transfer coefficient, etc., are also written in the

code


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FIGURE 3.1 FLOW SHEET FOR AMMONIA WATER SYSTEM


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CHAPTER 4

MATERIAL BALANCES

4.1 FLASH SEPERATOR

Assumptions:

Inlet mass flow rate = 1kg/s

Inlet ammonia composition = 0.50

Inlet water composition = 0.50

Vapour Pressure Data:

At 100C,

Vapour Pressure of Ammonia, = 4571 mmHgVapour Pressure of Water, = 11.5 mmHgEquations:

= = 1 = 1m*=ml*+ mv*From equation 1 & 2,

Pt= *+*From 3 & 5,

=

=

.

= 0.164


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From Equation 3,

=1-=.836

= =.1644571760

=.989=

=.. =.011Substituting,,,in equation 4,we get,ml= .5927 kg/s

mv= .4073 kg/s


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CHAPTER 5

ENERGY BALANCES

5.1 FLASH SEPARATER

Figure 5.1 FLASH SEPERATOR

Energy in = mLCPL TF +mV CPV TF

=[0.5927(4.58*0.164+4.22*0.836)*283+0.4073(2.1*0.989+1.86*0.023]

= 717.74+241.754

= 959.494 kW

Liquid

QL = mLCPLTh1

= [0.5627*(4.58*0.164+4.22*0.836)*283]

= 717.74 kW

Vapour


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QV = mVCPVTfv

= [0.4073*(2.1*0.989+1.86*0.011)*283]

= 241.754 kW

5.2 SUPER HEATER

Figure 5.2 SUPER HEATER

Inlet Energy = mvCpvTfv

= [0.4073*(2.1*0.989+1.86*0.011)*283]

= 241.754 kW

Energy Added = mvCpvT + mvRTfiln(p1/p2)

= mvCpv(Tti-Tfv) +mvRTtiln(p1/p2)

= [(0.4073*1.96*(50-10)) + (0.4073*8314/17.011*323*ln (1/10))]

= 31.93+148.15

= 180 kW

Outlet Energy = Inlet Energy +Energy Added

= 241.754+180

= 421.83 Kw


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5.3 TURBINE

Figure 5.3 TURBINE

Assuming the process is Adiabatic

Inlet Energy = Outlet Energy from the Super heater

Power produced =

[1

]

= .40738.314/17.0113231.31 [ 1 1101.311.3

]

W = 88.4 kW

Outlet Energy = Inlet Energy - Power produced

Inlet Energy = 421.83 kW

Power produced = 88.4kW

Outlet Energy = 421.83 -88.4

= 333.43 KW

Outlet Energy = mvCpTto

333.43 = 0.4073*4.47*Tto

Tto =183K

` Tto = - 900 C


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5.4 ABSORBER

Figure 5.4 ABSORBER

Inlet Energy = Energy from the Turbine + Energy from the Heat Exchanger

= mvCpTto +mLCpTh2

= 333.43 + 686.13

= 1019.56

Outlet Energy = Inlet Energy

Outlet temperature = Outlet energy

= mCpTa

= 1*4.4*Ta

Ta =232 K

Ta = -410C

Hence Outlet Energy = 1019.56 kW


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5.5 REFRIGERATION

Figure 5.5 REFRIGERATION

Inlet Energy from the absorber +Energy Added = Outlet of Absorber

1019.56 +Energy Added = 1113.2

Energy Added = 93.64 kW

Energy Added = mCpT

Assuming the air inlet temperature =400C

Assuming the air outlet temperature =200C

Mass flow rate of air = Energy Added/ (Cpair*Tair)

93.64 = mair*1*(40-20)

mair = 4.682kg/s

Mass Flow Rate = 4.682kg/s

5.6 HEAT EXCHANGER

Figure 5.6 HEAT EXCHANGER


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Inlet energy from the Flash Drum

At 100C

Q = mLCPTh1

= 0.5927*(4.58*0.164+4.22*0.836)*283

= 717.74 kW

Inlet energy to the HE from the Absorber

At -200C

Q = mCPTc1

= 1*4.4*253

= 1113.2 kW

Outlet Energy from the absorber to the Vaporiser

At -130C

Q = mLCPTc2

= 1*4.4*260

= 1144 kW

To find Th2:

Th2 = (Inlet EnergyEnergy to the Vaporizer)/mLCP

=(..)()

..

= 264 K

= -90C

Therefore, the outlet energy from HE to Absorber is = mLCPTh2

=.5927*4.385*264 =686.13 kW


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5.7 VAPOURISER

Figure 5.7 VAPOURISER

Energy added = Energy required to raise the Temperature + Latent Heat of vaporisation

=m*Cp*(Tf-Tc2) + mv*( + )=1*4.4*(283-260) + .4073*(.989*1200 + .011 * 2406)

=595.36 Kw

Energy added = 595.36 kW


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CHAPTER 6

DESIGN OF SHELL AND TUBE HEAT EXCHANGER

Mass flow rate of hot stream,mh = 0.5927 kg/s

Mass flow rate of hot stream,mc = 1 kg/s

Inlet temperature of hot stream,Th1 = 10oC

Outlet temperature of hot stream,Th2 = -9oC

Inlet temperature of cold stream,Tc1 = -20oC

Outlet temperature of hot stream,Tc2 = -13oC

Hot stream average temperature,ThAvg = 0.5oC

Cold stream average temperature,TcAvg = -16.5o

C

Property Table

S.No Property Unit Hot stream Cold stream

1. Cp J/kgoC 4280 4400

2. Kg/m 940.48 840

3. Pa.s (10- ) 1.49 1.65

4. K W/m.oC .565 .5587

Assumptions

Overall heat transfer unit,U0 = 600 W/m2.K.

Length of the tubes,L = 4 m.

Outer diameter of the tube,Do = 20 mm.

Inner diameter of the tube,Di = 16 mm.


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Baffle cut = 25%

Tube pitch,Pt = 1.25Do

Pt = 1.25*20

Pt = 25 mm

Thermal conductivity of cupro-nickel alloys = 50 W/m.K.

Number of Shell-side passes = 1

Number of Tube-side passes = 4

Logarithmic Mean Temperature Difference,

LMTD =()()

LMTD =(())(())

(())(())

LMTD = 16.27 oC

R =

R = 10(9)13(20)R = 0.3684

S =

S =

S = 0.633

Using temperature correction factor chart,

Ft = .97

Correct LMTD = Ft*LMTD

= .97*16.2

() = 15.714 oCHeat load Q = ()

= 1*4400(-13-(-20))

= 30.8 kW


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Assuming Overall heat transfer unit,U0= 600 W/m2.K

Heat transfer area,

Ah = ()Ah =

.

Ah = 3.25 m2

Assuming total heat transfer area =3 m2

Area of 1 tube =

DoL

= 3.14*0.02*4

= 0.251 m2

Total number of tubes required,

Nt =

Nt =

.Nt = 11.9 tubes

For Triangular Pitch,

Bundle Diameter,

Db = Do .

.

Db = 0.02* ..

.

Db = 0.116 m

Using a split-ring floating head,

From Shell bundle clearance chart,

Bundle diameter clearance,

BDC = 0.0477 m

Shell diameter,

Ds = Db + BDC

Ds = 0.116 + .0477


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Ds = 0.163 m

Tube side Coefficient

Tube cross sectional area,

A = DiA =

*0.016

A = 2.01*10-4m2

Tube per pass,

Tp =

.

Tp = 11.9/4

Tp = 3 tubes

Total flow area of tubes,

At = A*Tp

At = 2.01*10-4*3

At = 6*10-4m2

Tube-side velocity,

Vt = ()

() ()

Vt =

Vt = 1.984 m/s

Reynolds Number for tubes:

= = ... = 16178

Prandtl Number for tubes:

=


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= ..

= 12.98

= .= 250Using heat transfer factor chart, we get,

= 3.1 10 =(). = (). = .5587. 3.1 10 16178 (12.98). = 4081 W/m2.K

Shell-side Coefficient:

Baffle Spacing,

Bs = =

.

Bs = 0.0408 m

Shell-side flow area,

As =

As =

() 0.1630.0408

As = 1.33*10-3m2

Shell-side equivalent diameter,

De = 1.1 (2 0.9172)De =

.. (0.025 0.9170.02)

De = 0.0142 m

Shell-side velocity,

Vs = ()

flow() ()Vs = ..10.


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Vs = 0.473 m/s

Shell-side Reynolds Number:

= = ..473.. = 4242.7

Shell-side Prandtl Number:

=

= .. = 11.27

Using Shell-side heat transfer factor chart,

= 8.0*10-3 =(). = (). = .. 8 1 0 4242.7 (11.27). = 3028.3 W/m2.K

Overall heat transfer coefficient, Uo

1 =

1 +

+

2

1 =

13028.3 +

2016 4081+

0.0220162 5 0 1

=0.00068Uo = 1468 W/m2.K


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Tube side pressure drop

= 8 +2.52

Using Tube-side friction factor chart, we get,

=3.1*10-3 = 4 8 3 . 1 1 0 40.016 + 2.5

8401.9842

= 4 8 3 . 1 1 0 40.016 + 2.58401.984

2

= 57.54

= 8.35 Shell-side pressure drop

= 8

2 Using Shell-side friction factor chart, we get,

= 5.7*10-2 = 8 2

=8 5 . 7 1 02 40.0408 0.1630.0142 940.480.4732

2

= 54.05 kPa = 7.84 kPa

6.1 VISUAL BASIC CODING

Public Class shell_tube

to find corrected lmtd

Public Function Ft(ByVal th_1 As Integer, ByVal th_2 As Integer, ByVal tc_1 As Integer, ByVal tc_2 As

Integer, ByVal n As Integer) As Single

Dim p, r, rp, x, a, b, c, d, e, f, g, h, num, den As Single

p = (tc_2 - tc_1) / (th_1 - tc_1)

r = (th_1 - th_2) / (tc_2 - tc_1)

rp = (r * p - 1) / (p - 1)

rp = rp ^ (1 / n)x = (1 - rp) / (r - rp)

a = Math.Sqrt(r ^ 2 + 1)

b = a / (r - 1)

c = Math.Log((1 - x) / (1 - r * x))


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num = b * c

d = 2 / x - 1 - r + a

e = 2 / x - 1 - r - a

den = Math.Log(d / e)

Ft = num / den

f = (th_1 - tc_2) - (th_2 - tc_1)g = Math.Log((th_1 - tc_2) / (th_2 - tc_1))

h = f / gFt = Ft * h

End Function

Function fun_shell_dia(ByVal bun_dia As Single) As Single

Dim a, b, c, d As Single

b = bun_dia * 0.001If Head_type.SelectedIndex = 0 Then

a = 10 * b + 8

ElseIf Head_type.SelectedIndex = 1 Then

a = 38

ElseIf Head_type.SelectedIndex = 2 Then

a = 27 * b + 44.4ElseIf Head_type.SelectedIndex = 3 Then

a = 5 / 0.55 * b + 47.25 / 0.55

End If

Return ((a + bun_dia) * 0.001)

End Function

Public Function baffle15(ByVal b15 As Single) As Single

Dim a, b As Single

a = Math.Log(b15)

If b15 300 And b15 < 1000 Then

b = -0.3368 * a + 0.02376

Elseb = 0.001242 * a ^ 3 - 0.03154 * a ^ 2 + 0.08592 * a - 1.777

End If

b = Math.Exp(b)

Return b

End Function


Dim a, b As Single

a = Math.Log(b15)

If b15 300 And b15 < 1000 Then

b = -0.2962 * a - 0.6128

Elseb = 0.002014 * a ^ 2 - 0.1825 * a - 1.495

End If

b = Math.Exp(b)Return b

End Function


Dim a, b As Single

a = Math.Log(b15)If b15 300 And b15 < 1000 Then

b = 0.1113 * a ^ 2 - 1.709 * a + 3.721

Elseb = -0.003228 * a ^ 2 - 0.111 * a - 1.853


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End If

b = Math.Exp(b)

Return b

End Function


Dim a, b As Singlea = Math.Log(b15)

If b15 300 And b15 < 1000 Then

b = -0.2795 * a - 1.065

Else

b = -0.004517 * a ^ 2 - 0.08661 * a - 2.182End If

b = Math.Exp(b)

Return b

End Function

Public Function baffle_ht_15(ByVal b15 As Single) As Single

Dim a, b As Singlea = Math.Log(b15)

If b15


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Return b

End Function

Public Function tube_heatlam(ByVal nrelam As Single, ByVal ld As Single) As Single

Dim a, b As Single

a = Math.Log(nrelam)

If ld = 24 Thenb = -0.6419 * a - 1.335 + 0.82

ElseIf ld > 24 And ld 48 And ld 120 And ld 240 And ld


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b = 2.675

End If

ElseIf pitch_combo.SelectedIndex = 1 Then

If tube_passes.Text = 1 Then

a = 0.215

b = 2.207ElseIf tube_passes.Text = 2 Then

a = 0.156b = 2.291

ElseIf tube_passes.Text = 4 Then

a = 0.158

b = 2.263

ElseIf tube_passes.Text = 6 Thena = 0.0402

b = 2.617

ElseIf tube_passes.Text = 8 Then

a = 0.0331

b = 2.643

End IfEnd If

c = d * (n / a) ^ (1 / b)

Return (c)

End Function

Public Function Nre(ByVal d As Single, ByVal v As Single, ByVal rho As Single, ByVal mu As Single) As

Single

Return (d * v * rho / mu)

End Function

Public Function Npr(ByVal cp As Single, ByVal mu As Single, ByVal k As Single) As Single

Return (cp * mu / k)

End Function

Public Function heat_coeff(ByVal k As Single, ByVal d As Single, ByVal nre As Single, ByVal npr As

Single, ByVal jh As Single)Return (jh * k / d * nre * (npr) ^ 0.33)

End Function

Public Function calc_Uo(ByVal ht1 As Single, ByVal hs1 As Single, ByVal d As Single, ByVal di As

Single, ByVal k As Single,

ByVal foul_t As Single, ByVal foul_s As Single) As Single

Dim a, b, c As Single

a = 1 / hs1 + foul_s + foul_t * d / di + d / di / ht1

b = d / (2 * k) * Math.Log(d / di)

c = a + b

c = 1 / cReturn (c)

End Function

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) HandlesButton1.Click

'heat load

Dim delT, qh, Ah, Db, tube_per_pass As SingleDim Area_1_tube, No_tube, shell_dia, tube_csa As Single

Dim tube_flow_area, tube_vel, tube_nre, tube_npr As Single

Dim tube_heat_factor, ht As Single

Dim shell_csa, shell_vel, de, shell_nre, shell_npr As Single

Dim shell_heat_factor, hs, act_Uo As Singleqh = heatload(hot_flow.Text, hot_cp.Text, th1.Text, th2.Text)

delT = Ft(th1.Text, th2.Text, tc1.Text, tc2.Text, 1)

Ah = qh / (Uo.Text * delT)

r_ht_area.Text = Ah

'res_A.Text = AhArea_1_tube = Math.PI * d_o.Text * Len_tube.Text


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No_tube = Ah / Area_1_tube

r_ntubes.Text = No_tube

Db = bundle_diam(d_o.Text, No_tube)

shell_dia = fun_shell_dia(Db * 1000)

tube_csa = Math.PI / 4 * d_i.Text ^ 2

tube_per_pass = No_tube / tube_passes.Texttube_flow_area = tube_per_pass * tube_csa

tube_vel = cold_flow.Text / (tube_flow_area * cold_density.Text)tube_nre = Nre(d_i.Text, tube_vel, cold_density.Text, cold_viscosity.Text)

tube_npr = Npr(cold_cp.Text, cold_viscosity.Text, cold_k.Text)

If tube_nre < 2000 Then

tube_heat_factor = tube_heatlam(tube_nre, Len_tube.Text / d_i.Text)

Elsetube_heat_factor = tube_heat_turb(tube_nre)End If

ht = heat_coeff(cold_k.Text, d_i.Text, tube_nre, tube_npr, tube_heat_factor)

tube_pitch.Text = 1.25 * d_o.Text

baffle_space = shell_dia / (baffle_spacing.Text - 1)

shell_csa = (tube_pitch.Text - d_o.Text) / tube_pitch.Text * shell_dia * baffle_space

shell_vel = hot_flow.Text / (shell_csa * hot_density.Text)If pitch_combo.SelectedIndex = 0 Then

de = 1.1 / d_o.Text * (tube_pitch.Text ^ 2 - 0.917 * d_o.Text ^ 2)

ElseIf pitch_combo.SelectedIndex = 1 Then

de = 1.27 / d_o.Text * (tube_pitch.Text ^ 2 - 0.785 * d_o.Text ^ 2)

End If

shell_nre = Nre(de, shell_vel, hot_density.Text, hot_viscosity.Text)

shell_npr = Npr(hot_cp.Text, hot_viscosity.Text, hot_k.Text)

If baff_cut.SelectedIndex = 0 Then

shell_heat_factor = baffle_ht_15(shell_nre)

ElseIf baff_cut.SelectedIndex = 1 Then



shell_heat_factor = baffle_ht_35(shell_nre)ElseIf baff_cut.SelectedIndex = 3 Then


End If

hs = heat_coeff(hot_k.Text, de, shell_nre, shell_npr, shell_heat_factor)

act_Uo = calc_Uo(ht, hs, d_o.Text, d_i.Text, mat_k.Text, cold_fouling.Text, hot_fouling.Text)

jft = tube_friction(tube_nre)

delpt = tube_passes.Text * (8 * jft * Len_tube.Text / d_i.Text + 2.5) * cold_density.Text * tube_vel ^ 2 / 2

If baff_cut.SelectedIndex = 0 Then

jfs = baffle15(shell_nre)

ElseIf baff_cut.SelectedIndex = 1 Thenjfs = baffle25(shell_nre)


jfs = baffle35(shell_nre)ElseIf baff_cut.SelectedIndex = 3 Then

jfs = baffle45(shell_nre)

End Ifdelps = 8 * jfs * (shell_dia / de) * (Len_tube.Text / baffle_space) * hot_density.Text / 2 * shell_vel ^ 2

Uo_calc.Text = act_Uo

tube_pres.Text = delpt / 6895

shell_pres.Text = delps / 6895

rt_ht.Text = htrt_npr.Text = tube_npr

rt_nre.Text = tube_nre

rt_vel.Text = tube_vel

rs_hs.Text = hs

rs_npr.Text = shell_nprrs_nre.Text = shell_nre


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rs_vel.Text = shell_velEnd SubEnd Class

Figure 6.1 SHELL AND TUBE APPLIACTION SOFTWARE


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6.2 PICTORIAL REPRESENTATION

Figure 6.2 SHELL AND TUBE HEAT EXCHANGER


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CHAPTER 7

CONCLUSION

Thus we understand the combined power and refrigeration cycle produces the

maximum efficiency, recovery of maximum energy from the waste heat source to produce

both the power and the refrigeration. The power produced is about 88.4 KW.A computer

program based on the VISUAL BASIC code for the optimisation of the design of shell and

tube heat exchanger has been developed to design the shell and heat exchanger. From this

we understand this application is very effective for calculating the heat load, LMTD,

Number of passes and Number of tubes required, heat transfer coefficient, pressure drop,

heat transfer area and Overall heat transfer coefficient, etc.


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REFERENCES

1. Lu.S., Goswami, (1994) Performance Assessment of Ammonia-Water Based Power

and Refrigeration Cogeneration Cycle.

2. Gunnar Tamm, D. Yogi Go swami (2002) Novel Combined Power and Cooling

Thermodynamic Cycle for Low Temperature Heat Sources.

3. M. M. Rashid, O. A. Beg (2001) and A. Aghagoli Utilization of waste heat in combined

power and ejector refrigeration for a solar energy source.

4. Na Zhanga, Noam Loir (2006) Methodology for thermal design of novel combinedrefrigeration/power binary fluid systems, International Journal of Refrigeration.

5. Ram Darash Patel, Priti Shukla (2000) International journal of research in aeronautical

and mechanical engineering, Thermodynamics analysis and optimization for a combined

power and refrigeration cycle.

6. Lu.S., Goswami, (2002) Theoretical based combined power /refrigeration cycle at low

refrigeration temperature.

7. Xu Feng, Goswami D. Yogi, Bhagwat Sunil S., (2000), A combined power/cooling

cycle, Energy 25 (2000) 233246.


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CHAPTER 1

INTRODUCTION

Homogeneity in multi-phase reaction systems are generally carried out to maintain

the uniform suspension of solids and also to maintain the stability in reaction kinetics, on

other hand homogeneity is maintained to reduce the amount of catalyst consumption. Need

of homogeneity is mainly to control the value of conversion and also to reduce the

operating fluctuations of the reactor. Due to formation of dead zones a pasty catalyst form

as lumps on the wall side of the reactor. When those lumps enter the fluidization area

where the reaction takes place a sudden rise in the temperature of the reactant takes place.

To prevent reactor from running out of condition, formation of lumps should be prevented.

Main drawback in forced circulation fluidized bed reactor is the formation of dead zones.

Due to this reason maintaining of the homogeneity is tedious in the fluidized bed reactor.In order to maintain the homogeneity, change in design aspects or placing agitator is

needed. Literatures were reviewed to find the solution for the above problem. The possible

solutions obtained are listed below:

Varying the different variables like

Catalyst pellet size Fluidization velocity Viscosity of the feed Feed inlet condition Placing an external mixing equipment like agitator While changing the above variables there may be some drawbacks. When the size

of the catalyst is changed from 1mm surface area reduces and increases the catalyst

consumption rate. Actual operating condition of the reactor is 15 to 16C.Astemperature is inversely proportional to viscosity thus it affects the operating

condition of the reactor and also it affects the grade off the polymer


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While varying the flow rate it is directly proportional to the fluidization velocity.When flow rate increases fluidization velocity increases entrainment of particles

take place and it increases the circulation rate but decreases the conversion.

If the flow rate is decreased then it will affect the fluidization velocity thus itinduces the formation of hot spots. In case of altering the feed conditions the

reaction rate and kinetic will affect. Reactant is first precooled using refrigerant

before it is sent in to the reactor. Maintaining the refrigerant rate is one of the ways

to maintain process temperature of the reactor. But there is some fluctuation in the

refrigerant rate since the reaction is exothermic. On considering the above

drawbacks and also by referring the various literatures, finally the best method of

overcome this issue is placing a spiral type agitator suspended at one end. The

hydrodynamic study was carried out for the starch system using biocatalyst and the

solid distribution was calculated for varying liquid flow rate and solid

concentrations.The correlation was developed between the Solid circulation

number, Reynolds Number and the Velocity number.


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CHAPTER 2

LITERATURE REVIEW

Akifumi Kato, Ohtake et al (1999) have studied Anchor Agitator for gaseousphase polymerisation vessel.This study employed an Anchor agitator for uniform

and effective stirring of the Fluidised bed zone of a polymerization vessel in a

gaseous phase polymerisation reaction.

Jr grace, c j lim, cmh brereton and j chaouki (2001) Circulating fluidized bedreactor design and operation. This study is helps to know about the Introduction to

circulating fluidised bed reactor

Jukka koskinen, Espoo; Henrik Andtsjo, et al (1997) have studied Methods forpolymerizing olefin in a fluid bed reactor. This study employed the homogeneity

of solids in the fluidized bed reactor and also how the polymerization reaction is

carried out.

Biao Wang, Tao Li, Qi-wen Sun, Wei-yong Ying, and Ding-ye Fang (2001) studieda Solid Concentration in Circulating Fluidized Bed Reactor for the MTO Process.

The effects of radial distance, axial distance, superficial gas velocity, initial bed

height on solid concentration in the bed and the effects of distributor shape and

porosity on solid concentration is discussed.

Joelle Aubin, Cathrine Xuereb et al (2005) have studied Design of multipleimpeller stirred tanks for the mixing of highly viscous fluids using CFD .This

study helped to know the effect of multiple Intermig impeller configuration on

hydrodynamics and mixing performance in stirred tank of computational fluid

dynamics


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CHAPTER 3

MATERIALS AND METHODS

3.1 MATERIALS USED

The set up for the circulating fluidised bed was fabricated, with the

specifications of about Riser diameter 28 cm and the Riser height 40 cm.The agitator is

spiral type. This spiral agitator has one end suspended and other end as free end. The spiral

agitator was chosen because the hollow portion of the agitator does not affect the

fluidization taking place inside the reactor. The disturbance produced by this type is

comparatively less when compared to other type of agitators in mixing viscose liquids.

This agitator was connected to the motor by the shaft connected to the spiral structure. The

dimension of the spiral agitator was made according to the ratio of reactor dimension. The

specification of the agitator with Diameter 23 cm, Pitch 8 cm, Width 1.25 cm, Thickness

0.4 cm and no. of. Turns 3.5.

Figure 3.1 SPIRAL AGITATOR

The viscose fluid used to carry out the hydrodynamic analysis in the lab scale model was

starch solution. Thus the properties of starch as follows

Molecular formula :(C12H22O11)n


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Density : 1.5gm/cm3

Thus the viscosity of starch solution was chosen to carry out the hydrodynamic analysis in

the lab scale model. And the handling of starch solution is also comparatively easy with

high availability and cost effective.

For the solid catalyst particle the bio catalyst was used to carry out the

polymerization reaction. The bio catalyst was chosen because the specific gravity of the

bio catalyst is low and helps in the better polymerization.

3.2 METHODS USED:

The response which should be noted was the solid composition in the product

stream. The uniformity of the solid composition in the product stream denoted that there is

no lumping of catalyst solid particles taking place. Thus the problem of solid lumping can

be avoided by this analysis.

The variables in the process are:

Flow rate Solid loading

Thus for the varying concentration and flow rate the solid composition is

measured. The concentration of feeding solution is 10% and 20% starch solution and the

flow rate as 300,350,400,450 and 500 ml/sec. For every value of Concentration and flow

rate the solid composition was measured.


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CHAPTER 4

Figure 4.1 EXPERIMENTAL SETUP

4.1 EXPERIMENTAL PROCEDURE:

The liquid is pumped in to the reactor and the circulation of the fluid is made by the

continued running of the pump. The required flow rate is fixed by adjusting the pump

regulator for one value of Q. The measured quantity of solid was taken and added to the

circulating liquid. The sample of 100ml of liquid along with solid in the circulation stream

was taken at the intervals of 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 minutes. The solids present in

the sample was separated, dried, and weighed. Thus the weights of the solid particles were

noted for the corresponding time intervals. The concentration in terms of Kg of solids

present/ m3 of sample collected was calculated. This procedure is repeated for with and

without agitator and for each and every concentration and flow rate. Thus the plot of

concentration versus time can be used to show the uniformity in solid composition.


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TABLE 5.3 SOLID LOADING=4 KG & 10% STARCH SOLUTION

FLOW RATE

ml/sec SOLID LOADING kg

CONC

gm/lit

300 4 27.5

350 4 37.6

400 4 42.3

450 4 58.6

500 4 66.9


FLOW RATE

ml/sec

SOLID LOADING

kg

CONC

gm/lit

300 3 42.6

350 3 66.7

400 3 73.56

450 3 89.8

500 3 112.3


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Figure 5.1 CONCENTRATION (gm/lit) Vs. FLOW RATE (ml/sec)(without stirrer)

0

10

20

30

40

50

60

70

80

90

100

110

120

250 300 350 400 450 500 550

C

ONCENTRATION

(gm/lit)

FLOW RATE

(ml/sec)

WITHOUT STIRRER

20% SOLUTION & 4 kg

LOADING

20% SOLUTION & 3 kg

LOADING

10% SOLUTION & 4 kg

LOADING

10% SOLUTION & 3 kg

LOADING


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WITH STIRRER





S.NO FLOW RATE ml/sec CONC gm/lit DEL_P N/m2

1 300 21.6 1238.6

2 350 27.6 1518.1

3 400 39.6 1658.4

4 450 48 1869.7

5 500 55.2 2017.5

S.NO FLOW RATE ml/sec CONC gm/lit DEL_P

6 300 43.2 2366.8

7 350 46.8 2588.1

8 400 57.6 2861.5

9 450 63.6 3335.8

10 500 82.8 3611.3


11 300 28.8 1847.34

12 350 38.4 2019.7

13 400 46.4 2365.7

14 450 59.2 2526.7

15 500 67.2 2783.3


16 300 48 3752.556

17 350 65.6 4022.127

18 400 76.8 4578.705

19 450 97.6 5170.786

20 500 103.2 5730.871


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Figure 5.2 CONCENTRATION (gm/lit) Vs. FLOW RATE (ml/sec)

Figure 5.3 PRESSURE DROP (N/m2) VS FLOW RATE (ml/sec)

0

10

20

30

40

50

60

70

80

90100

110

120

250 300 350 400 450 500 550

CONCENTRATION(gm

/lit)

FLOW RATE (ml/sec)

WITH STIRRER20% solution & 4 kg

loading

20% solution & 3 kgloading10% solution & 4 kg

loading10% solution & 3 kg

loading

0

1000

2000

3000

4000

5000

6000

7000

250 350 450 550PRESSUREDROP

(N/m2)

FLOW RATE

(ml/sec)

WITH STIRRER

20% solution & 4 kg

loading20% solution & 3 kgloading10% solution & 4 kg

loading

10% solution & 3 kgloading


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CORRELATION

= 1.337*().*().*.

+ . 8735 .

Where,

Solid Circulation Number,= ( ) ()

()

Velocity Number,=

Reynolds Number,

=

Ratio = Length to Diameter ratio of the Riser.

Correlation was developed between the Solid Circulation Number, Reynolds

Number, Velocity Number and (L/D) ratio of the riser. From the Correlation, we come into

conclusion that the Solid Circulation rate increases with the increase in the viscosity of the

fluid and also with the increase in the velocity. It increases with the decrease in the

terminal settling velocity of the particle which intern shows that when the particle size is

reduced, the Solid Circulation rate increases. And also the solid circulation rate increases

with the increase in the (L/D) ratio..


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CHAPTER 8

CONCLUSION

The hydrodynamics studies were conducted for the circulating Fluidized bed using

stirrer for starch solution and bio catalyst. The effect of flow rate, fluid properties such as

viscosity, density and the solid loading on the solid circulation rate and the pressure drop

were studied. Hence the usage of agitator thus removes the dead zones, and prevents the

lump formation. The correlation was developed between the Solid number, Reynolds

Number and the Velocity number.


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REFERENCES

1. Akifumi Kato, Ohtake; et al (1999) have studied Anchor Agitator for gaseous phase

polymerisation vessel.

2.Biao Wang, Tao Li, Qi-wen Sun, Wei-yong Ying, and Ding-ye Fang (2001) studied aSolid Concentration in Circulating Fluidized Bed Reactor for the MTO Process.

3. Grace Jr, C J Lim, Cmh Brereton and J Chaouki, Circulating fluidized bed reactor

design and operation.

4. Joelle Aubin, Cathrine Xuereb et al (2005) have studied Design of multiple impeller

stirred tanks for the mixing of highly viscous fluids using CFD.

5. Jukka koskinen, Espoo; Henrik Andtsjo, et al (1997) have studied Methods for

polymerizing olefin in a fluid bed reactor.

6. P.Natarajan, R.Velraj, R.V.Seeniraj (2001) have studied Hold up and solid circulations

rate in liquid solids circulating fluidized bed.

7.Siva lingam Amanda and Dr.T.Kannadasan Effect of Fluid Flow Rates on

Hydrodynamic Characteristics of Co-Current Three Phase Fluidized Beds with Spherical

Glass Bead Particles.

8. Thomas Ward, Asher Metchik et al (2008) have studied Viscous fluid mixing in a tiltedtank by period shear.

studies on waste heat recovery system and design of shell and tube heat exchanger using visual basic...

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